A timezone -12 icon is represented with a foldout map icon and on the edge of the map there is a circle with a -12 written inside. The map will have straight lines on both sides, but on the top and bottom there will be a zig zag pattern to show it's foldout component.

This is a Timezone -12 Filled icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 13,700 icons, all in the same style and quality.